Inflatable water-sports board with raised protrusions along its sides

ABSTRACT

An inflatable water sports board has internal spacer threads separating upper and lower faces. The water sports board has side portions free of internal spacer threads. When the water sports board is inflated the side portions expand in a part-circular shape, forming ridges above and below the respective upper and lower faces.

FIELD OF THE INVENTION

The present invention relates to inflatable water-sports boards such as surfboards, paddleboards, windsurfing boards, kitesurfing boards and the like.

BACKGROUND TO THE INVENTION

It is known to create water craft and water-sports boards from inflatable materials. The internal structure of such boards is created by two layers of ‘drop stitch’ fabric base yarns, connected by internal spacer threads or space yarns.

The drop stitch fabric base yarns are typically formed of a tightly woven polyester material, providing strength and stability to upper and lower surfaces. The internal spacer threads, also composed of polyester material, are generally perpendicular to the base yarn layers and are arranged in a dense array across the length and breadth of the base yarn layers.

There is typically a small gap between an outer edge of the base yarn fabric and the outermost spacer threads. This gap, which is generally in the order of 5 mm, allows for the connection of side walls (known as ‘rails’) of a board to the edges of the base yarn layers.

The smallness of this gap allows the board to maintain a generally flat upper surface and lower surface from edge to edge even when inflated to a high internal pressure.

Previously published patent applications US2009/078186, US2009/0079757, US2017/0197691, DE102017000759, and WO2013/175160 all disclose inflatable water sports board having typical gaps and rails at the edges, forming semi-circular side rails when inflated.

SUMMARY OF THE INVENTION

The present invention has proceeded from research by the inventors showing that improved hydrodynamic performance of a board can be achieved if the upper surface and lower surface are not flat from edge to edge, but rather have outwardly extending protrusions near side rails of the board.

According to one aspect of the present invention there is provided an inflatable water-sports board having an internal structure comprising an upper fabric layer and a lower fabric layer, the upper fabric layer being connected to the lower fabric layer by a plurality of spacer threads, the thickness of the water-sports board being defined by the length of the spacer threads; the water-sports board having side portions extending between the upper fabric layer and the lower fabric layer, the side portions being free of spacer threads, the side portions having an external perimeter having a length between two and three times the thickness of the water sports board.

It will be appreciated that when the board is inflated the side portions will form a convex curved portion on outer sides of the board. The convex curved portion extends around an arc of between about 220° and 260°, in contrast to the arc of 180° formed by a semicircular side rail. The convex curved portion will have a diameter of between about 1.05 and 1.3 times the thickness of the water sports board.

In accordance with a second aspect of the present invention there is provided an inflatable water-sports board having an upper surface, a lower surface, and side rails, wherein when the board is inflated the lower surface has a generally flat portion extending between two side portions, each of the side portions being convex, the flat portion extending through at least 50% of the width of the board, the side portion extending below a level of the flat portion.

In accordance with a third aspect of the present invention there is provided an inflatable water-sports board having an upper surface, a lower surface, and side rails, wherein when the board is inflated the upper surface has a generally flat portion extending between two side portions, each of the side portions being convex, the flat portion extending through at least 50% of the width of the board, the side portion extending above a level of the flat portion.

The convex side portion preferably extends along between 50% and 90% of the length of the board.

The inflated board may have a central thickness defined at a midpoint of the board. It is preferred that the convex side portion has a diameter between 105% and 130% of the central thickness of the inflated board.

BRIEF DESCRIPTION OF THE DRAWINGS

It will be convenient to further describe the invention with reference to preferred embodiments of the present invention. Other embodiments are possible, and consequently the particularity of the following discussion is not to be understood as superseding the generality of the preceding description of the invention. In the drawings:

FIG. 1 is a schematic perspective of an inflatable board in accordance with the present invention, shown in an uninflated condition;

FIG. 2 is a plan view of the inflatable board of FIG. 1;

FIG. 3 is a schematic cutaway view of the inflatable board of FIG. 1, shown in a collapsed condition;

FIG. 4 is a schematic cutaway view of the inflatable board of FIG. 1, shown in an inflated condition;

FIG. 5 is an enlarged cross section of a portion of the inflatable board of FIG. 1; and

FIG. 6 is a schematic cutaway view of a portion of the inflatable board of FIG. 1, showing layers of construction.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

FIGS. 1 to 4 show a stylized view of an inflatable board 10 having an upper surface 12, a lower surface 14, a trailing edge 16, and a leading edge 18. The upper surface 12 is connected to the lower surface 14 by a rail 20 which extends around a periphery of the inflatable board 10.

The upper surface 12 and the lower surface 14 each have a main portion 22 which is substantially flat.

The rail 20 has a rear portion 24 which extends around the trailing edge 16 of the inflatable board 10 and extends along sides of the inflatable board 10 about 10% to 15% of the length of the inflatable board 10 measured from the trailing edge 16 to the leading edge 18.

The rail 20 has a front portion 26 which extends around the leading edge 18 of the inflatable board 10 and extends along the sides of the inflatable board 10 about 20% to 25% of the length of the inflatable board 10.

The rail 20 has a side portion 28 extending along each side of the inflatable board 10 between the rear portion 24 and the front portion 26.

The arrangement is such that the side portions 28 of the rails 20 combine with lateral side portions of the upper surface 12 and lower surface 14 to form a convex curved portion 30 along each side of the inflatable board 10 when the board is inflated, as shown in FIGS. 4 and 5.

The convex curved portion 30 is generally part-circular in cross section. The convex curved portion 30 has a diameter between 5% and 30% larger than a thickness of the inflatable board 10, the thickness being measured between the upper surface 12 and the lower surface 14 at a midpoint of the inflatable board 10.

It will be appreciated that the convex curved portions 30 form elongate protrusions relative to the upper and lower surfaces 12, 14, the protrusions being aligned in a longitudinal direction of the inflatable board 10.

The main portion 22 of each of the upper and lower surfaces 12, 14 extends between the rear portion 24 and the front portion 26 of the rail 20, and between the convex curved portions 30 on either side of the main portion 22.

The internal structure of the inflatable board 10 which leads to the formation of the convex curved portions 30 will be described with reference to FIG. 6.

FIG. 6 shows a portion of the internal structure of an inflatable board, with an upper layer 32 of drop stitch base yarn fabric providing support for the upper surface 12 of the inflatable board 10, and a lower layer 34 of drop stitch base yarn fabric providing support for the lower surface 14 of the inflatable board 10. The upper layer 32 is connected to the lower layer 34 by a plurality of internal spacer threads 36.

Each of the upper layer 32 and the lower layer 34 have two outer lateral edges 38.

In the prior art, the internal spacer threads 36 extend nearly to the outer lateral edges 38. The upper layer 32 and lower layer 34 each have an outer lip which is sufficient to bond a rail 20 thereto. In practice, this lip is about 5 mm wide.

By way of contrast, in the present invention as shown in FIG. 6, the internal spacer threads 36 are spaced from the outer lateral edges 38 by a gap 40, which is in the order of 20 mm in the preferred embodiment. It is anticipated that a gap of at least 15 mm will provide a beneficial effect.

Upon inflation, the gaps 40 form a section of material which is unconstrained by internal spacer threads 36.

The result can be seen in FIGS. 4 to 6. The portions of the upper layer 32 and lower layer 34 that are constrained by the internal spacer threads 36 form flat surfaces with a fixed thickness equal to the length of the spacer threads 36. These support the main portions 22 of the upper and lower surfaces 12, 14.

The unconstrained portions of material inflate so as to minimize the ratio of volume to surface area; that is, they adopt a part-circular convex shape. This represents the convex curved portions 30.

The relative size of the convex curved portions 30 is determined by the ratio of the gap 40 to the length of the internal spacer threads.

FIG. 5 shows a portion of inflatable board 10 with the board having a thickness t, the convex curved portion 30 having a radius r, and the spacer threads 36 representing a chord subtended by an arc θ. It will be appreciated that if θ is between 100° and 140° then the convex curved portion 30 will extend around an arc between 220° and 260°. For an arc of 220° the ratio R of the diameter of the curved portion 30 to the length of the spacer threads 36; that is, 2 r:t ; will be about 1.05. For an arc of 260° the ratio R will be about 1.3.

For an arc of 220° the perimeter of the convex curved portion 30 will be about twice the length of the spacer threads 36. For an arc of 260° the perimeter of the convex curved portion 30 will be about three times the length of the spacer thread 36. It is considered that these represent the most useful range of sizes for the convex curved portion 30.

It will be appreciated that an inflatable board 10 constructed in this fashion will have side portions which extend above the level of the upper surface 12 and below the level of the lower surface 14 by between 2.5% and 15% of the thickness of the inflatable board 10.

By way of example, the inflatable board 10 of the drawings has a thickness of 120 mm. The diameter of the convex curved portions 30 is 140 mm. The side portions thus extend 10 mm (about 8%) above and below the upper and lower surfaces 12, 14 respectively. In this embodiment the upper surface 12 and the lower surface 14 each have a width of 610 mm, with the perimeter of the convex curved portion being about 295 mm, which means that when fully flat as shown in FIG. 3 each side portion 28 extends about 147 mm away from the lateral edges 38.

It will be appreciated that (a) the length of the convex curved portions 30; (b) their longitudinal position relative to the trailing edge 16 and leading edge 18; and (c) their diameter relative to the thickness of the inflatable board 10, can all be determined by the size and location of the gaps 40.

Modifications and variations as would be apparent to a skilled addressee are deemed to be within the scope of the present invention. 

1. An inflatable water-sports board having an internal structure comprising an upper fabric layer and a lower fabric layer, the upper fabric layer being connected to the lower fabric layer by a plurality of spacer threads, the thickness of the water-sports board being defined by the length of the spacer threads; the water-sports board having side portions extending between the upper fabric layer and the lower fabric layer, the side portions being free of spacer threads, the side portions having an external perimeter having a length between two and three times the thickness of the water sports board.
 2. An inflatable water-sports board as claimed in claim 1, wherein when the board is inflated the side portions form a convex curved portion on outer sides of the board, the convex curved portion extending around an arc of between about 220° and 260°.
 3. An inflatable water-sports board as claimed in claim 1, wherein the convex curved portion has a diameter of between about 1.05 and 1.3 times the thickness of the water sports board.
 4. An inflatable water-sports board having an upper surface, a lower surface, and side rails, wherein when the board is inflated the lower surface has a generally flat portion extending between two side portions, each of the side portions being convex, the flat portion extending through at least 50% of the width of the board, each side portion extending below a level of the flat portion.
 5. An inflatable water-sports board as claimed in claim 4, wherein each convex side portion extends along between 50% and 90% of the length of the board.
 6. An inflatable water-sports board as claimed in claim 4, wherein the inflated board has a central thickness defined at a midpoint of the board, and each convex side portion has a diameter between 105% and 130% of the central thickness of the inflated board.
 7. An inflatable water-sports board having an upper surface, a lower surface, and side rails, wherein when the board is inflated the upper surface has a generally flat portion extending between two side portions, each of the side portions being convex, the flat portion extending through at least 50% of the width of the board, each side portion extending above a level of the flat portion.
 8. An inflatable water-sports board as claimed in claim 7, wherein each convex side portion extends along between 50% and 90% of the length of the board.
 9. An inflatable water-sports board as claimed in claim 7, wherein the inflated board has a central thickness defined at a midpoint of the board, and each convex side portion has a diameter between 105% and 130% of the central thickness of the inflated board. 